Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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FXUS62 KRAH 131107
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
707 AM EDT SUN JUL 13 2014

.SYNOPSIS...A HIGHLY ANOMALOUS UPPER LEVEL TROUGH WILL DIG SOUTHEAST
FROM CANADA INTO THE EASTERN UNITED STATES EARLY THIS WEEK AND
PERSIST THROUGH MID TO LATE WEEK.

&&

.NEAR TERM /TODAY AND TONIGHT/...
AS OF 130 AM SUNDAY...

A RELATIVELY DRY/SUBSIDENT AIRMASS WILL PERSIST OVER THE REGION
TODAY...ON THE EASTERN PERIPHERY OF AN UPPER LEVEL RIDGE EXTENDING
EAST FROM THE CENTRAL PLAINS INTO THE SOUTHEAST STATES. A DEEP
/HIGHLY ANOMALOUS/ UPPER LEVEL LOW DIGGING SOUTHEAST FROM CENTRAL
CANADA INTO THE UPPER GREAT LAKES WILL RESULT IN STRENGTHENING
CYCLONIC FLOW ALOFT ACROSS THE OH VALLEY AND MID-ATLANTIC THIS
AFTERNOON INTO TONIGHT. GIVEN THAT THE BEST FORCING WILL REMAIN WELL
N/NW AND THAT DIURNAL DESTABILIZATION WILL BE MARGINAL (AT BEST)...
EXPECT DRY CONDITIONS TO PREVAIL IN MOST AREAS THROUGH TONIGHT.
WILL CONTINUE TO INDICATE A SLIGHT CHANCE OF CONVECTION IN THE FAR
NW PIEDMONT WHERE INCREASINGLY NW FLOW ALOFT WOULD ALLOW UPSTREAM
CONVECTION TO PROPAGATE INTO THE N/NW PIEDMONT FROM THE MOUNTAINS.
OTHERWISE...EXPECT CONDITIONS SIMILAR TO YESTERDAY ALBEIT SLIGHTLY
WARMER WITH HIGHS IN THE LOWER 90S. LOWS TONIGHT ALSO A FEW DEGREES
WARMER...IN THE LOWER 70S. -VINCENT

&&

.SHORT TERM /MONDAY AND MONDAY NIGHT/...
AS OF 245 AM SUNDAY...

EXPECT AT OR ABOVE NORMAL CHANCES FOR CONVECTION MONDAY AFT/EVE INTO
MON NIGHT AS CYCLONIC FLOW ALOFT STRENGTHENS OVER THE REGION IN THE
PRESENCE OF AN INCREASINGLY MOIST/UNSTABLE AIRMASS...ESPECIALLY IN
THE N/NW PIEDMONT IN CLOSER VICINITY TO SMALL AMPLITUDE WAVES
EMBEDDED IN STRONGER FLOW ALOFT OVER THE OH VALLEY AND MID ATLANTIC.
EXPECT HIGHS SIMILAR TO PREVIOUS DAYS...THOUGH PERHAPS SEVERAL
DEGREES COOLER IF CONVECTION /OUTFLOW/ IS PRESENT PRIOR TO PEAK
HEATING. LOWS MON NIGHT SIMILAR OR SLIGHTLY WARMER THAN TONIGHT...
IN THE LOWER 70S.

SEVERE POTENTIAL: MODERATE DESTABILIZATION IS EXPECTED MON AFTERNOON
ALONG AND EAST OF A PRE-FRONTAL TROUGH ORIENTED SW-NE FROM WADESBORO-
ROXBORO...THOUGH ONLY MARGINAL DESTABILIZATION IS EXPECTED IN THE NW
PIEDMONT WHERE A DRIER LOW-LEVEL AIRMASS WILL BE PRESENT. DEEP-LAYER
SHEAR WILL BE 10-20 KT OVER CENTRAL NC MON AFT/EVE...THOUGH PERHAPS
INCREASING TO ~30 KT IN THE FAR NW PIEDMONT MON NIGHT. GIVEN
MARGINAL INSTABILITY...WEAK DEEP LAYER SHEAR...WEAK DCAPE...AND THAT
NOCTURNAL STABILIZATION WILL BE WELL UNDERWAY WHEN MORE ORGANIZED
UPSTREAM CONVECTION COULD PROPAGATE INTO THE AREA...ANTICIPATE
LITTLE POTENTIAL FOR SVR WX IN CENTRAL NC AT THIS TIME...AND THAT
THE 15% SVR PROB EXTENDING EAST OF THE APPALACHIANS INTO NORTHWEST
NC ON THE SPC DAY2 OUTLOOK APPEARS GENEROUS AT BEST. -VINCENT

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
AS OF 159 AM SUNDAY...

AN ANOMALOUS MID/UPPER TROUGH FOR THE MIDDLE OF SUMMER IS EXPECTED
TO BUILD OVER THE GREAT LAKES THIS PERIOD. THE MAIN COLD FRONT
ASSOCIATED WITH THIS TROUGH IS SLATED BY THE MODELS TO APPROACH THE
MOUNTAINS FROM THE NORTHWEST LATE MONDAY. A PRE-FRONTAL TROUGH IS
ALSO FORECAST MONDAY AFTERNOON AND EVENING TO BE LOCATED OVER THE
PIEDMONT. MONDAY SHOULD BE THE HOTTEST DAY THIS WEEK BEFORE THE
DRAMATIC COOLING. HIGHS SHOULD REACH THE 90S FOR ALL ZONES. THE BEST
CHANCE OF PM THUNDERSTORMS WILL BE OVER THE NORTHWEST PIEDMONT
MONDAY.

THE MAIN COLD FRONT IS THEN EXPECTED TO PUSH ACROSS OUR REGION
TUESDAY. SHOWERS AND THUNDERSTORMS WILL BE LIKELY... MAINLY TUESDAY
AFTERNOON INTO THE NIGHT AS THE COLD FRONT AND POTENTIALLY A WEAK
WAVE OF LOW PRESSURE FOCUS CONVECTION. THE MODELS AGREE IN MODERATE
TO STRONG INSTABILITY DEVELOPING OVER CENTRAL AND EASTERN NC TUESDAY
AFTERNOON. DEPENDING ON TIMING OF THE FRONT... STRONG TO ISOLATED
SEVERE STORMS MAY EVOLVE WITH THE MAIN THREAT FROM BOTH DAMAGING
WIND GUSTS AND LARGE HAIL. SHOWERS AND THUNDERSTORMS ARE LIKELY TO
CONTINUE TUESDAY NIGHT INTO EARLY WEDNESDAY AS THE FRONT SLOWLY SAGS
SE THROUGH THE REGION. LOCALLY 2 INCHES OF RAIN MAY ALSO OCCUR
ESPECIALLY OVER THE CENTRAL AND EASTERN ZONES TUESDAY AFTERNOON AND
NIGHT.

MODELS CONTINUE TO SUGGEST SOME DRYING WEDNESDAY INTO THURSDAY WITH
A REDUCTION IN POP AS THE MAIN FRONT DIES OUT TO OUR SOUTH.
HOWEVER... THERE ARE ALREADY INDICATIONS THAT THE MID/UPPER TROUGH
AXIS MAY REMAIN ALONG OR JUST WEST OF OUR REGION SUPPORTING
ADDITIONAL SHOWERS AND POSSIBLY THUNDERSTORMS RETURNING LATE IN THE
WEEK. DAYTIME HIGHS SHOULD REALLY BACK OFF WEDNESDAY THROUGH FRIDAY
WITH 80-85 EXPECTED (ALMOST 10 DEGREE BELOW NORMAL). LOWS SHOULD BE
MOSTLY IN THE 60S (SOME UPPER 50S NORTH ON WEDNESDAY AND THURSDAY) -
WHICH WOULD BE 5-10 DEGREES BELOW NORMAL.
&&

.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
AS OF 705 AM SUNDAY...

24-HR TAF PERIOD: VFR CONDITIONS WILL PREVAIL THROUGH THE TAF PERIOD
IN MOST LOCATIONS. EXCEPTIONS INCLUDE REDUCED VISBYS AND CEILINGS
ASSOC/W FOG AT THE FAY/RWI TERMINALS WHICH WILL RAPIDLY LIFT AND
BURN OFF BY 12-13Z THIS MORNING...AND A POTENTIAL FOR ISOLD
CONVECTION AT THE INT/GSO TERMINALS DURING THE LATE AFTERNOON AND
EVENING HOURS (21-00Z). CALM OR LIGHT SOUTHERLY WINDS THIS MORNING
WILL BECOME SSW/SW AT 5-10 KT THIS AFTERNOON.

LOOKING AHEAD: EXPECT WIDESPREAD SHOWERS AND THUNDERSTORMS MONDAY
THROUGH THE END OF THE WORK WEEK IN ASSOCIATION WITH A HIGHLY
ANOMALOUS UPPER LEVEL TROUGH OVER THE EASTERN CONUS. -VINCENT

&&

.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$

SYNOPSIS...VINCENT
NEAR TERM...VINCENT
SHORT TERM...VINCENT
LONG TERM...32
AVIATION..VINCENT


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